Stencil sheet



Patented Nov. 3, 1931 SH INJ'IRO HORII, 0F KANDA-KU, TOKYO, JAPANSTENCIL SHEET No Drawing. Application filed August 1, 1930, Serial No472,500, and in Japan June 28, 1930.

My invention relates to improvements in stencil sheets for use 1nduplicating manuscript and typewritten documents, drawings ofpolysaccharides and a tempering agent,.

such as naphthenic acid glycerides, chlorinated naphthalene, fatty acidof Tsubaki oil or a mixture of them.

It has also been proposed to produce a stencil sheet of loose-fiberedtissue coated with I cellulose acetate plastified and stabilized byacetanilid, combined with a softening agent, such as glycerine anddiethyl phthalate.

According to the present invention the 2 stencil sheetcomprises a baseof fibrous material having a coating including esters ofpolysaccharides, a metallic soap of naphthenic acid, a suitabletempering agent.

A metallic soap of napthenic acid is prepared by heating and combiningtogether the equivalent portions of naphthenic acid and an oxide ofmetal, or by the double-decomposition of a solution of an alkali soap ofnaphthenic acid with a solution of some salt of metals, such asaluminum, iron, calcium or magnesium.

The film of cellulose esters as well as of the other esters ofpolysaccharides, however, is highly unstable and considerabledeteriorates when stored for a long period of time.

Moreover, it is extremely sensitive to sunlight. A clear film exposedfor a few days only becomes brittle so that it will not withstand mildbending even without cracking. The use of oils and plasticizers willextend the life, but eventually failure will occur. The fatty oilsbecomerancid on exposure and make the film sticky. Consequently, astencil sheet having such a coating is unstable for ,the esters.

It is common practice to neutralize the free acid and the acid which maybe produced afterwards with feeble alkalies, such as urea and otheramines, but these substances make them unsafe because of producing aharmful product which decreases the colloidal propcity of the esters,and acts to decompose the esters, as the majority of the stabilizing materials exert an alkaline reaction upon the esters. The choice of thestabilizing material is in practice preferably restricted to such aswill not harmfully affect the coating of the stencil sheet of the kindabove referred to. Now, it has been found that metallic soaps ofnaphthenic acid, for example calcium naphthenate, will overcome theabove defects. The metallic soaps of naphthenic acid are the mostefiective stabilizers for the esters of polysaccharides. They exert noadverse action on the esters of polysaccharides U and combine with thefree acid present in the esters, forming salts of the metals in volvedand liberating the naphthenicacid. The naphthenic acid produced is afeeble acid of saturated constitution and exerts no saponifying actionon the esters of polysaccharides, improving the durability and toughnessof the cellulosic film. Metallic soaps of naphthenic acid and naphthenicacid also are the plasticizers for the esters of polysaccharides.Furthermore, it has been found to be more effective to use them incombination with an alkyl ester of naphthenic tempering agents, but thealkali soap are weak alkalies, and they act on the cellulose esters,decreasing their colloidal property. The alkali soaps of oleic acidcombine with the free acid present in the'cellulose esters, and therewill be produced the salts of the metals and free oleicacid. The oleicacid is a stronger acid than naphthenic acid and is an unsaturated one.Consequently, it accelerates the ranciditv of the oils present and alsoexerts the saponification of the cellulose esters of the coating.Therefore. the use of alkali soaps. or other soaps of fatty acids, givesno good results.

As already described. the stencil sheet pro-.

duced in accordance with the present invention is very durable. owing toits stability. and the stencil is also remarkably soft and pliablebecause of the combined use of an alkyl ester of naphthenic acid with ametallic soap of naphthenic acid giving a clear stencil by the pressureof a writing machine.

In carrying out the invention into practice. first the esters ofpolysaccharides. such as starch acetate. mannan acetate. celluloseacetate. cellulose stearate and cellulose ni-- trate, are dissolved in aVolatile solvent. such as ether. alcohol. acetone. ethvl acetate. butylacetate, butyl alcohol. benzine. benzol or a mixture of them. and thenthe solution is mixed with a solution of a metallic soap of naphthenicacid dissolved in a suitable tion is coated on a base material such as Japane e yoshino paper.

The proportions of the ingredients may vary according to severalcircumstances. By the way of example particulars are given as follows EmI Parts by weight Fatty acid of Tsubaki oil 5 Paraffin oil. 5

Ewample II Parts by weight Cellulose acetate Mannan acetate 5 Acetone 50Cyclohexanon 1O Ethyl acetate 20 Calcium naphthenate 1 5 Ethylnaphthenate 10 Naphthenic acid glycerides 1-0 Chlorinated naphthalene 5Fatty acid of Tsubaki oil 5 The above coating compositions may bediluted with any suitable solvents to the desired consistency.

The term esters of polysaccharides is intended to include not only oneof definite esters of polysaccharides, but also a mixture of them.

lVhat I claim is 1. A stencil sheet adapted for stencilizing bypressure, comprising, a base of fibrous material having a coatingincluding esters of polysaccharides, a metallic soap of naphthenic acid,and a tempering agent.

2. A stencil sheet adapted for stencilizing by pressure, comprising abase of fibrous material having a coating including esters ofpolysaccharides, a metallic soap of naphthenic acid, an alkyl ester ofnaphthenic acid, and a tempering agent.

3. A stencil sheet adapted for stencilizing by pressure, comprising abase of fibrous material having aqcoating including esters ofpolysaccharides, a metallic soap of naphthenic acid, ethyl naphthenate,and a tempering agent.

4. A stencil sheet adapted for stenciliz- SHINJIRO HOB-II.

Cellulose nitrate 20 Alcohol 2O Ethyl acetate; 30 Butyl acetate 10Calcium naphthenate 1 5 Ethyl naphthenate 5 Cyclohexanon "5 20 Benzol 2OButyl phthalate A 2 Naphthenic acid glycerides 15 Tsubaki oil 10

